The US Centers for Disease Control and Prevention on Friday released guidelines for schools that focus on five key Covid-19 mitigation strategies: 1) the universal and correct wearing of masks; 2)  physical distancing; 3) washing your hands; 4) cleaning  facilities and improving ventilation, and 5) contact tracing, isolation and quarantine.

Vaccines and testing are not among the "key" strategies the agency lays out, calling them "additional layers" of Covid-19 prevention.

But the new recommendations come amid a national debate about when and how to reopen schools, even as fear of spreading the coronavirus continues and a push to prioritize teachers for vaccinations grows.

Contct tracing: measure the impact to your employees should someone be impacted by Covid-19.